I wrote a letter once and never sent it. Instead, I embedded the words in another project.
We do this sort of thing all the time. We place bits of our anger, our excitement, our passion and our frustration into everything we do - even if it's not the direct cause. We leave our thoughts and emotions across all we do and that's simply human.
A debate I've been reading around critical vs. creative thinking is missing the fact that emotion colours both approaches. Regardless of the side of the brain you favour, pretending that the final output isn't coloured by emotion is naive.
When folks talk about following your passion, or putting passion into your work, it isn't always about pursuing the dream. (I'm never going to write famous mystery novels; I just like thinking about doing that!) Sometimes it is simply about finding that piece that makes you spring out of bed in the morning - learning something new; working in an environment that stimulates you; showcasing a skill; etc. - and letting that be the hook that allows you to put more of yourself into your day.
Creativity comes from passion, belief and curiosity. Critical thinking can spring from the same well. Mentoring is about both sides of that coin including how we feel about the ideas and outcomes.
Expressing yourself and your emotions makes both the project, day and outcome that much sweeter for everyone.